THE  POSITION  OF  PERCOPSIS 


BY 


CLAUDE  LEIST 

A.  B.  University  of  Illinois  1918 


THESIS 


Submitted  in  Partial  Fulfillment  of  the  Requirements  for  the 

Degree  of 


MASTER  OF  ARTS 


IN  ZOOLOGY 


IN 

THE  GRADUATE  SCHOOL 

OF  THE 

UNIVERSITY  OF  ILLINOIS 


1921 


Digitized  by  the  Internet  Archive, 
in  2015 


https://archive.org/details/positionofpercopOOIeis 


TABIJE  OF  CONTENTS 


I.  Introduction 

II.  The  External  Anatomy 

III.  The  Internal  Anatomy 

1.  Alimentary  Tract 

a.  The  mouth  and  pharyngeal  region 
h.  The  alimentary  canal 

2.  The  Sv;im  Bladder 

3.  The  Uro-genital  System 

4.  The  Nervous  System 

a.  The  brain 

IV.  Discussion 

V.  Conclusion 

VI.  Bibliography 

VII.  Explanation  of  Plates 


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THE  POSITION  OP  PERCOPSIS 


I.  Introduction  | 

The  position  of  Percopsis  in  its  relationship  among  j 

fishes  has  never  "been  definitely  settled.  From  the  time  it  was 
first  described  by  Agassiz  to  the  present  it  has  been  placed  by 
ichthyologists  within  at  least  three  divisions  of  teleosts,  namely, 
with  physostomous  fishes  closely  related  to  the  Saltnonidae,  with 
the  Haplomi , and  with  the  Acanthopterygii.  Gttnther  places  it  in 
his  order  Physostomi,  in  a family  Percopsidae  just  above  the  Sal- 
mon! dae.  By  most  later  ichthyologists  it  is  thought  to  be  a prim- 
itive Acanthopterygian  which  has  just  made  a transition  from  those 
Physostomous  fishes  akin  to  the  Isospondyli  and  Haplomi  (Jordan 
and  Evermann)  or  an  ancestral  form  of  the  present  Acanthopterygians. 
Boulenger  alone  places  the  Percopsidae  among  the  Haplomi,  of  which 
he  says,  ''They  may  be  regarded  as  hi^ly  specialized  members  (of 

i 

the  Haplomi)  having  evolved  in  Ihe  direction  of  the  Acanthoptery- 
gii.'' Goodrich  agrees  with  Jordan  and  Evermann,  while  Regan, 

5 

thou^  he  does  not  definitely  place  them,  says  the  study  of  their 
anatomy  does  not  confirm  the  view  that  they  are  related  to  percoid 
fishes  of  the  Centrarchidae  and  Percoideae. 

This  paper  deals  with  the  anatomy  of  Percopsis  guttatus; 


its  purpose  being  to  determine  more  accurately  the  position  of  the 
fish  in  the  system.  It  describes  the  external  appearances,  the 


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"brain,  and  the  anatomy  of  the  alimentary  tract,  uro-genital  sys- 
tem, and  swim-bladder.  An  attempt  was  made  to  study  thoroughly 
the  blood  vascular  system,  but  the  state  of  preservation  of  the 
specimens  made  that  impossible.  Some  parts  of  the  circulatory 
system  of  the  coelom  and  viscera  could  be  made  out,  but  that  of 
the  head,  the  branchial  arches  excepted,  was  utterly  impossible 
with  the  material  at  hand.  There  was  not  time  to  study  the  skele 
ton,  so  skeletal  parts  were  ignored.  However,  the  fact  has  not 
been  overlooked  that  the  skeleton  is  of  great  importance  in  class 
if ication. 


II.  The  External  Anatomy 

Percopsis  guttatus  is  a snail  fish,  rather  slender,  and 
never  attaining  more  than  six  inches  in  length.  Of  the  thirty 
odd  specimens  which  I had,  the  largest  measured  not  more  than  5 
inches  in  length  (127  mm).  The  animal  is  sligihtly  compressed  and 
tapers  gradually  posteriorly,  terminating  in  a strongly  forked 
caudal  fin.  The  depth  of  the  body  is  about  one-sixth  of  the  total 
length,  or  one-fifth  the  length  if  the  caudal  fin  be  not  included. 
The  greatest  width  is  conte-ined  about  eight  times  in  the  total 
length,  the  width  into  the  depth  about  one  and  a third  times.  The 
greatest  width  of  the  body  is  just  in  front  of  the  insertion  of 
the  pectoral  fin,  the  greatest  depth  sli^tly  behind  this  inser- 
tion, and  the  least  depth  is  just  in  front  of  the  caudal  fin. 

Thus  the  ratio  of  the  greatest  to  the  least  depth  is  about  three 


VI 


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to  one.  Finely  toothed  ctenoid  scales  cover  the  tody  with  the 
exception  of  the  head,  this  "being  naked. 

The  "back  and  dorso- lateral  surface  of  the  fish  is  a 
sooty  grey  in  color  mottled  with  large  "black  spots.  These  "black 
spots  are  placed  in  a linear  arrangement  the  entire  length  of  the 
trunk  and  the  caudal  peduncle.  The  pignent  of  the  skin  is  more 
dense  on  the  posterior  part  of  the  "body.  The  "belly  is  a silvery 
white . 

The  lateral  line  organ  appears  as  a white  streak  on  the 
"body.  It  is  "bordered  "by  a dark  pi^ent,  and  it  first  becomes 
prominent  at  a point  about  midwe^y  between  the  subopercular  angle 
and  the  dorso-median  line.  It  extends  posteriorly,  keeping  always 
in  the  area  of  the  dorso- lateral  half  and  terminating  just  at  the 
base  of  the  caudal  fin. 

The  head  is  comparatively  large,  conical,  and  somewhat 
broad.  Large  opercular  openings  give  the  head  a broader  s.ppear- 
ance  than  it  really  has.  The  length  of  the  head  is  one-fourth 
the  length  of  the  entire  animal;  its  greatest  width  when  the 
operculae  are  closed  is  equal  to  that  of  the  trunk,  but  the  depth  | 
is  sli^tly  less  than  the  depth  of  the  trunk.  The  width  of  the  I 
head  is  contained  in  the  length  about  tv/ice,  its  depth  one  and  || 

two-fifths.  The  mouth  is  small  and  terminal,  the  upper  margin  | 

protruding  but  sli^tly  over  tine  lower.  The  upper  margin  is  made 
up  of  the  premaxillary  alone.  The  premaxillary  is  in  length  about 
one-fourth  that  of  the  head,  and  the  angle  of  the  mouth  is  some- 
what in  front  of  and  some  distance  below  the  nares.  The  nares 


-4- 


are  double.  Each  naris  is  divided  by  a partition  giving  an  enter-  | 
and 

io£/posterior  aperture  to  each.  They  lie  nearer  the  mid-dorsal  ! 

line  than  to  the  dorsal  margin  of  the  eyes,  but  are  sli^tly  nearer  I 

i 

the  eyes  than  to  the  tip  of  the  snout.  The  eyes  are  lateral  and 
a little  high  upon  the  head.  The  ventral  margin  of  the  eye  is 
above  the  middle  of  the  side  of  the  head;  its  diameter  is  a little 
less  than  one-half  the  depth  of  the  head,  v;hile  the  inter-orbital 
space  is  one-half  the  width  of  the  head.  There  are  six  bran  Chios  t- 
egals;  the  opercular  openings  are  wide;  the  gill  membranes  free. 

The  opercular  apparatus  is  complete,  has  a smooth  margin  a,nd  its 
angle  is  not  spinous  but  sharp.  Feather-like  pseudobranchia  are 
present.  The  head  has  cavernous  spaces  in  it  filled  with  raucous, 
much  like  that  of  the  Gymnocephala  of  Europe  (Jordan  e.nd  Evermann, 
1896)  . 

There  are  two  dorsal  fins;  the  anterior  has  rays,  the 

posterior  is  an  adipose  fin.  The  anterior  dorsal  fin  is  supported 

by  two  small  spiny  rays  in  front,  and  these  are  followed  by  nine  j 

to  eleven  soft  articulated  rays.  The  first  spiny  ray  is  about  j 

one-third,  the  second  spiny  ray  about  three-fourths  the  length  of  |j 

the  longest  dorsal  ray.  Both  spiny  rays  are  firmer  and  somewhat  | 

}! 

stiffer  than  the  soft  articulated  rays.  These  spiny  rays  of  Per-  !| 
copsis  are  much  weaker  than  those  spines  commonly  found  in  Acan- 
thopterygian  fishes.  However,  they  show  the  characteristics  of 
true  spines.  The  most  anterior  of  the  soft  rays  in  the  dorsal 
fin  differs  from  the  other  soft  rays  in  this  respect,  it  is  long- 
est and  does  not  branch.  The  remaining  soft  rays  divide  twice 


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dicho tomously  before  reaching  the  distal  end.  All  of  the  soft  j 

rays  are  articulate.  The  fin  is  placed  a little  nearer  the  anter- 
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I 

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midway  between  the  anterior  dorsal  and  the  caudal  fin.  It  is 
small  and  lies  close  to  the  body. 

The  pectoral  fins  articulate  with  the  body  almost  below 
the  sharp  posterior  angle  of  the  suboperculum.  Each  has  twelve 
rays.  Their  length  falls  but  little  short  of  extending  as  far 
posteriorly  as  the  anal  opening.  The  ventral  fins  are  abdominal 
in  position,  being  slightly  nearer  the  anal  opening  than  to  the 
juncture  of  the  gill  membranes,  and  are  almost  directly  beneath  the 
anterior  dorsal.  Each  has  eight  soft  rays. 

One  spine  and  five  soft  rays  (the  a,rticulate  rays  split 
at  the  distal  end)  support  the  anal  fin.  The  spine  is  a little 
more  than  half  the  length  of  the  fin.  The  caudal  fin  is  horaocer- 
cle,  strongly  forked,  long  and  slender.  The  caudal  peduncle  and 
the  caudal  fin  comprise  almost  two -fifths  the  length  of  the  fish. 

I 

The  measurements  of  a specimen  of  Percopsis  guttatus  I 

is  as  follows: 


Length  of  fish-  - - - - - 
Length  of  caudal  peduncle 
Length  of  caudal  fin  - - 
Depth  of  caudal  peduncle 
Depth  of  body  ------ 

V/idth  of  body---  - - - 


I 

i 

96  mm.  (Caudal  fin  not  included) 

27  mm. 

20  mm. 


7 mm. 
19  mm. 


14  ram. 


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28  mm. 


Length  of  head 
Width  of  interorhital  space  - - - 6 mm. 

Length  of  snout  - --  --  --  --10  mm. 
Length  of  maxillary  - --  --  --  7 mm. 
Length  of  mandible  - --  --  --  - 5 mm. 


An  excellent  cut  of  P.  guttatus  may  be  found  in 
Agassiz  ’’Lake  Superior,”  1853. 


III.  Internal  Anatomy 
1.  Alimentary  System 

(a)  The  mouth  and  pharyngeal  region:-  The  mouth  open- 
ing is  small.  The  p remaxi 1 lari es  slightly  protrude  over  the 
dentaries.  The  teeth  are  small,  villifotta,  and  more  densely  com- 
pact together  in  the  area  nearest  the  juncture  of  the  right  and 
left  premaxillaries.  On  the  dentaries  the  teeth  are  much  more 
numerous  and  more  evenly  distributed  over  the  oral  surface  of 
the  bones. 

Just  posterior  to  the  teeth  are  the  two  breathing 
valves.  They  are  membraneous  organs,  each  semi-lunar  in  shape, 
the  upper  and  larger  valve  (maxillary  valve)  has  the  circular 
edge  attached  to  the  inner  margin  of  the  premaxillaries,  the 
loose  edge  of  the  valve  extending  across  from  tlie  base  of  one 
premaxillary  to  the  base  of  the  other.  The  lower  valve  (man- 


-7- 


dibular  valve)  is  smaller,  but  is  similarly  attached  to  the  den- 
taries. 

The  dorsal  part  of  the  mouth  arches  rapidly  posteriorly 
for  a short  distance,  then  horizontally  until  it  reaches  the  first 
gill  slit.  The  cavity  formed  by  the  arching  narrows  as  it  travels 
backward  because  of  the  space  taken  up  by  the  orbits,  to  again 
broaden  out  until  it  reaches  the  first  gill  cleft.  The  epithelial 
tissue  has  many  minute  longitudinal  folds.  There  are  no  teeth  in 
this  portion  of  the  mouth,  the  surface  being  smooth  to  the  touch. 
The  floor  of  the  mouth  anterior  to  the  first  gill  cleft  is  less 
deeply  hollowed  than  the  roof,  but  is  toothless  and  smooth. 

There  is  no  true  tongue.  The  copulae  of  the  second, 
third,  and  fourth  branchial  arches  as  well  as  the  branchial  arches 
themselves  bear  very  minute  villiform  teeth,  all  pointing  backward. 
Immediately  back  of  the  branchial  arches  the  oesophagus  begins. 

The  pharyngeal  region  of  the  roof  of  the  mouth  is  marked  off  from 
the  anterior  part  by  a deep  and  sha.rply  defined  transverse  groove 
at  right  angles  to  the  longitudinal  axis  of  the  body.  Just  pos- 
terior to  this  line  are  the  plate-like  superior  pharyngeal  bones. 
There  are  three  of  these  on  each  side  of  the  median  line  and  each 
bear  numerous  teeth.  The  posterior  margin  of  the  last  pharyngeal 
bone  marks  the  anterior  margin  of  the  oesophagus. 

(b)  The  alimentary  canal:-  The  alimentary  canal,  when 
viewed  from  the  exterior,  consists  of  three  well  marked  regions: 
the  oesophagus  and  stomach,  the  pyloric  caecal  region  of  the  intes- 
tine, and  the  simple  intestine.  The  canal  is  siphonal,  making  two 
distinct  sharp  bends  in  its  entire  length.  Beginning  at  the 


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-8- 


li 


pharyngeal  region,  it  extends  posteriorly  to  about  one-half  the 
length  of  the  body  cavity  where  it  suddenly  turns  toward  the  right, 
and  bending  upon  itself,  extends  anteriorly  to  the  cardiac  portion 
of  the  stomach.  There,  suddenly  turning  dorsally,  it  again  bends 
upon  itself  and  travels  posteriorly  to  the  end  of  the  body  cavity 
where  it  opens  to  the  exterior.  The  general  linear  outline  of  the 
canal  is  that  of  a complete  loop,  the  stomach  having  one  bend,  the 
intestine  one.  Its  whole  length,  however,  the  bends  being  drawn 
out,  will  scarcely  exceed  55  mm.  and  the  canal  when  empty  fills 
about  one- third  the  body  cavity. 

The  oesophagus  cannot  readily  be  distinguished  from  the 
stomach  for  the  one  gradually  blends  into  the  other.  But  the 
greater  part  of  the  oesophagus  has  uniformity  in  shape  that  aids 
in  distinguishing  it  from  the  stomach.  At  the  pharyngeal  area  it 
is  narrow,  gradually  dilating  in  the  central  portion  of  its  length, 
then  restricts  somewhat  to  again  become  broadened  before  it  enters 
the  stomach.  The  inner  membrane  hangs  in  simple  longitudinal 
folds.  The  length  of  the  oesophagus  is  normally  about  one-half 
that  of  the  stomach. 

Brom  its  cardiac  end,  the  stomach  extends  posteriorly 
to  about  one-half  the  length  of  the  coelom  where  it  makes  a sharp 
bend  toward  the  ri^t  and  then  quickly  ends  in  the  pylorus.  This 
gives  it  a ”J*'  shape  with  the  long  arm  (cardiac  portion)  a large 
distended  sack;  the  smaller  end  (pyloric  portion)  being  much 
smaller,  scarcely  extending  from  the  end  of  the  large  arm.  Here 
the  pyloric  valve  is  located.  The  abrupt  bend  of  the  stomach  and 
immediate  ending  in  a pyloric  valve  gives  no  chance  for  the  elonga- 


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-9- 


tion  of  the  posterior  part  of  the  stomach  into  a lar^e  pocket  so 
characteristic  of  those  Acanthopterygian  fishes  which  Rathke 
describes  as  inhabiting  the  fresh  waters  of  Europe,  the  structure 
which  he  calls  the  "Blindsack. •’ 

The  intestine  begins  at  the  pyloric  end  of  the  stomach: 
first,  as  a dilated  or  enlarged  tube  in  the  region  of  the  pyloric 
caecae,  then  as  a slender  tube  until  it  reaches  the  anus.  The  in- 
testine is  short  (about  twice  the  length  of  the  stomach  and  oesoph- 
agus combined)  never  coiled,  and  makes  only  one  bend,  forming  a 
loop,  one  arm  of  which  is  about  three  times  the  other,  but  the 
shorter  alone  receives  the  pyloric  caecae.  The  rectal  portion 
shows  little  differentiation,  being  only  slightly  larger  in  diam- 
eter than  the  slender  part  of  the  tube. 

Pyloric  caecae  are  present  in  the  section  of  the  intes- 
tine adjacent  to  the  stomach.  Their  number  varies  between  nine 
and  twelve  in  different  individuals.  These  caecae  are  evenly 
distributed  in  a linear  arrangement  on  both  sides  of  the  intestine, 
one  row  usually,  thou^  not  always,  extending  up  to  and  enveloping 
the  left  side  of  the  stomach,  the  other  is  looped  about  the  ven- 
tral side.  They  are  large,  being  about  one- third  the  diameter  of 
the  intestine  and  in  length  often  reaching  to  about  half  that  of 
the  stomach.  Each  has  its  individual  opening  into  the  intestine. 
Within  the  area  of  this  group  of  pyloric  caecae  the  intestine 
receives  the  bile  duct. 

There  is  a distinct  constriction  separating  the  stomach 
from  the  intestine,  ce.used  by  a band  of  circular  muscles  and  con- 
stitutes the  pyloric  phinxter. 


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-10- 


The  liver  is  very  compact,  closely  packed  in  the  anter- 
ior part  of  the  body  cavity.  It  extends  across  the  thorasic  floor 
of  the  cavity  and  well  upon  the  sides  covering  completely  the  an- 
terior cardiac  part  of  the  stomach  as  well  as  the  "bend”  of  the 
intestine.  It  has  two  lobes;  the  one  containing  the  greater  bulk 
extends  from  the  right  side  some  distance  into  the  left;  the  left 
lobe  is  smaller  but  more  marked  in  appearance.  These  lobes  how- 
ever are  never  very  conspicuous,  and  at  first  si^t  the  liver 
appears  to  be  a compact  triangle  of  tissue.  The  gall  bladder, 
though  almost  surrounded  by  liver  tissue,  is  however  distinct  and 
free  from  the  liver  and  can  be  dissected  out.  The  hepatic  duct 
enters  the  bladder  in  about  the  same  position  that  the  cholodocus 
leaves  it.  The  liver  is  extremely  vascular. 

Adjacent  to  the  gall  bladder  and  likewise  imbedded  in 
the  liver  is  the  pancreas;  an  oblong  structure  with  tv/o  small 
lobes  at  the  posterior  end  due  to  a partial  imprint  of  the  gall 
bladder  pressing  against  its  tissues.  I was  unable  to  determine 
the  exact  course  of  the  duct,  but  it  seems  to  follow  closely  that 
of  the  liver.  The  pancreas  is  very  easily  overlooked. 


2.  The  Swim  Bladder 


I 


The  swim  bladder  of  Percopsis  lies  outside  of  the  deeply 
pigmented  peritoneum,  dorsal  to  the  alimentary  tract  and  genital 
orgains,  and  Just  ventral  to  the  kidneys.  It  extends  almost  the 
whole  length  of  the  body  cavity,  being  a little  short  of  the  ex- 
treme anterior  of  the  cavity,  the  result  of  the  intervention  of 


j 


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-11- 


I 


the  head  kidneys  which  project  ventrally  from  the  dorsal  wall.  The 
swim  bladder  is  a simple  sack,  flattened  dorso-ventrally.  It  grad- 
ually narrows  from  the  anterior  end  to  the  posterior  until  it 
reaches  about  one-half  the  width  it  has  toward  the  cephalic  end. 

On  the  anterior  ventral  surface  is  a large  vascular  and  glandular 
area  (rete  mirable)  which  extends  over  the  anterior  ventral  surface 
to  about  one-third  the  distance  posteriorly  and  receives  its  arter- 
ial blood  from  a branch  of  the  coeliac  axis,  the  venous  blood  leav- 
ing it  throu^  a branch  of  one  of  the  mesenteric  veins.  These 
blood  vessels  are  supported  by  a mesentery  which  connects  with  the 
alimentary  canal,  but  there  is  no  trace  of  a pneumatic  duct  in  this 
mesentery  or  in  any  part  of  the  swim  bladder.  The  whole  bladder 
can  be  dissected  free  from  the  body  with  no  connection  with  the 
alimentary  canal  save  at  the  mesentery  which  bears  the  blood  vessels 
Gross  dissection  or  cross  sections  do  not  reveal  an  open  duct,  or 
any  trace  of  an  atrified  duct.  The  swim  bladder  has  no  connection 
with  the  head,  being  free  from  any  structure  of  the  head  or  anter- 
ior vertebrae  (i.e.  no  Weberian  apparatus  is  present). 

3.  The  Uro-Genital  System 

The  nephridia  of  Percopsis  are  situated  along  the  haemal 
area  of  the  coelom  outside  the  peritoneum  and  dorsal  to  the  swim 
bladder.  The  two  are  separated  from  each  other  by  the  haemal  ridge 
of  the  vertebral  column  and  are  united  to  each  other  only  at  the 


anterior  end  of  the  coelom  in  the  region  of  the  head  kidneys.  They 


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-12- 


are  divided  into  two  divisions  according  to  the  kind  of  tissue 
they  contain.  The  large  glandular  area  most  anteriorly  is  the 
pronephros  (head  kidney),  the  small  long  lohulated  structure  ex- 
tending from  the  head  kidney  posteriorly  is  the  mesonephros. 

The  head  kidneys  are  large,  lobulated,  glandular  masses 
of  tissue  in  the  anterior  part  of  the  coelom  and  are  united  by  a 
narrow  neck  of  like  tissue.  They  suddenly  grow  smaller,  becoming 
differentiated  into  the  long  slender  mesonephros.  The  mesonephros 
can  be  described  as  a thin  flat  slender  ribbon  with  the  mesonephric 
tissue  situated  in  swellings,  which  accommodate  themselves  to  the 
hollow  formed  by  the  concavity  of  each  vertebrae.  The  mesonephroi 
continue  posteriorly  carrying  the  urinary  ducts  (which  are  imbedded 
within  the  mesonephric  tissue)  with  them  until  they  reach  the  pos- 
terior wall  of  the  coelom.  Here  they  follow  the  curvature  of  the 
wall  ventrally,  and  finally  end  into  a small  conical  shaped  bladder. 
This  bladder  receives  each  of  the  two  urinary  ducts.  It  in  turn 
opens  into  the  genital  pore  by  means  of  a very  short  tube  or  duct. 

Each  kidney  receives  lateral  renal  arteries  from  the 
dorsal  aorta.  They  receive  their  venous  blood  from  the  ri^t  and 
left  subcardinals,  both  of  which  arise  from  the  caudal  vein.  These 
veins  and  the  post-cardinals  run  along  the  ventral  surface  of  the 
respective  right  and  left  kidney  until  the  latter  enter  the  sinus 
venosus.  The  urinary  ducts  lie  in  the  mass  of  kidney  tissue  near 
the  inner  margin  of  the  kidneys. 

The  gonads  consist  of  two  long  oblong  club-shaped  sa.cs 
united  at  the  posterior  end  by  a short  large  cylindrical  duct  that 
terminates  in  a genite,!  pore.  ?.Tien  at  the  hei^^t  of  sexual  activity 


!f®" 


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-13- 


the  ovaries  take  up  the  larger  part  of  the  body  cavity.  They  re- 
ceive their  arterial  blood  from  a ri^^t  and  left  genital  artery; 
the  right  of  these  being  a branch  of  the  artery  that  supplies  the 
rete  inirable,  the  left  from  the  left  gastric  artery.  The  genital 
veins  of  the  tv;o  sides,  so  far  as  I could  make  out,  are  separs-te, 
each  emptying  separately  into  the  sinus  venosus.  Among  all  the 
specimens  dissected,  I did  not  find  any  male. 

4.  The  Nervous  System 

(a)  The  brain^:-  The  brain  is  very  compact  and  larger 
in  proportion  to  the  body  than  in  most  fishes.  It  lies  in  a 
capacious  cavity  in  the  sku.ll  entirely  surrounded  by  a meninx 
which  fills  the  remainder  of  the  brain  case.  The  greatest  v/idth 
and  depth  of  the  brain  is  almost  equal.  In  a specimen  of  P.  gutta- 
tus,  116  mm.  long,  the  brain  measured  5 mm.  at  its  greatest  v;idth 
and  depth,  and  13.5  mm.  in  length  (the  olfactory  extension  not 
included).  With  the  olfactory  tract  included,  the  brain  is  about 
18  mm.  in  length. 

The  rhinencephalon  extends  forward  from  the  floor  of  the 
telencephalon  into  a slender  olfactory  tract,  the  olfactory  bulb 
following  the  nares  in  their  growth.  Thus  this  tract  is  enlarged 
into  a bulbus  olfactorus  at  the  nares,  so  that  the  bulbus  olfac- 
torus  v.'hich  contains  the  olfactory  nerve  is  some  distance  from  the 
telencephalon.  The  telencephalon  is  small,  bilobed,  each  lobe 


^Condition  of  material  at  hand  would  not  pemit  detailed  study  of 
cranial  nervae. 


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-14- 

conical  in  shape,  and  nearly  the  entire  mass  consists  of  corpus 
striatum.  The  ventricles  are  almost  obsolete  for  the  thin  pallial 
tissue  lies  almost  in  contact  v;ith  the  corpus  striatum. 

Ventral  to,  and  entirely  obscured  from  the  dorsal  as- 
pect by  the  optic  lobes  is  the  diencephalon.  In  the  anterior  part 
of  the  median  ventral  line  is  the  large  oval  body,  the  infundibulum, 
and  just  posterior  to  this  the  saccus  vasculosus.  I was  unable 
to  remove  the  hypophysis  from  the  base  of  the  skull,  so  only  the 
scar  was  left  on  the  ventral  side  of  the  infundibulum.  On  each 
side  of  the  infundibulum  is  the  lobi  inferiores. 

The  optic  lobes  (mesencephalon)  are  very  large.  They 
extend  anteriorly  some^i^at  over  the  posterior  part  of  the  telen- 
cephalon and  laterally  somewhat  on  either  side  of  the  anterior 
part  of  the  metencephalon.  The  optic  nerves  pass  anteriorly 
and  ventrally  from  the  optic  lobes  on  either  side  of  the  dien- 
cephalon crossing  each  other  just  in  front  of  the  infundibulum. 

This  chiasma  is  peculiar  in  that  there  is  a complicated  inter- 
lacing of  bundles  of  fibres.  I know  of  no  other  case  among 
Teleosts  where  as  complicated  an  interlacing  of  fibres  occurs. 

The  nearest  approach  to  it  is  in  Clupea  harengus  where  the  optic 
nerve  of  the  left  eye  passes  throu^  that  of  the  right^  that  is,  ^ 
the  nerve  separates  into  two  bundles  and  the  nerve  of  the  left 
eye  pa.sses  throu^  this  separation.  (Gottsche,  1835). 

Situated  posteriorly  in  the  dorso-median  line  and  adja- 
cent to  the  mesencephalon  is  the  single  lobed  metencephalon  (cere- 
bellum). It  is  more  elevated  than  the  optic  lobes  and  its  mass 


J 


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extends  slightly  between  them.  It  has  an  ovoid  conical  shape. 

The  medulla  oblongata  (myelencephalon)  is  massive.  It 
extends  anteriorly  some  distance  beneath  the  optic  lobes  and  pos- 
teriorly to  just  behind  the  origin  of  the  tenth  nerve.  Though 
broad  in  front,  it  gradually  tapers  posteriorly  and  suddenly  tapers 
into  the  spinal  cord.  The  fifth  and  seventh  nerves  ( trigeminalis 
and  facialis)  have  their  origin  in  the  anterior  lateral  aspect  of 
the  myelencephalon.  The  eighth,  ninth,  and  tenth  nerves  (acusticus, 
glossopharyngeal,  and  vagus)  follow  in  the  order  named  along  the 
lateral  margin  of  the  myelencephalon. 

IV.  Discussion 

Agassiz,  1653,  was  the  first  to  describe  Percopsis,  and 
throu^  him  it  bears  the  name  it  now  has.  The  naked  head,  abdom- 
inal ventral  fins,  and  adipose  fin  he  noticed  as  strikingly  Salmon- 
oid  in  type,  yet  the  ctenoid  scales,  mouth,  and  spiny  dorsal  and 
anal  fins  were  exceedingly  Percoid.  His  comment  on  the  fish  is 
as  follows:  "Now  my  new  genus  Percopsis  is  just  intermediate 

between  Ctenoids  and  Cycloids;  it  is  what  an  ichthyologist  at 
present  would  scarcely  think  possible,  a true  intermediate  type 
between  Percoids  and  Salmonidae.”  To  Agassiz  the  fish  v/as  dis- 
tinctly an  intermediate  type  betv/een  two  representative  types  of 
Teleostian  fishes,  those  of  the  Salmonidae  and  the  Percidae. 

In  shape,  one  cannot  say  that  the  fish  is  distinctly 
percoid  or  salmonoid.  It  is  rather  intermediate  of  the  two.  Its 
greatest  height  is  farther  anteriorly  than  is  usually  marked  in 


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i; 

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K •.  '■  .’  ' T u " ■ ■ '■''  ■'"'''  ••'■*  " ,.<«r-  *^-^Jf^'  ' "'”'  " 

i!.^.. ' j^::^x. ,i  . . \-'.i^j!s^^::- 


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vii  . yo^i  -0/^;tpp^X'O'^£(;^;  .bsfattCin^Xx:®  lo'^bi'op^c^^'  i 

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-16- 


the  salmon,  a characteristic  which  is  percoid.  However,  the  hody 
is  not  so  compressed  as  in  the  perches.^ 

The  external  anatomy  shows  a great  number  of  mixed  char- 
acters. The  two  spines  of  the  anterior  dorsal  fin  and  the  one  of 
the  anal  are  characteristic  of  the  Acanthopterygii . However,  a 
similar  small  fin,  similarly  placed,  thou^  v/ithout  spines,  occurs 
in  both  Cyprinidae  and  Salraonidae.  Again  a dorsal  fin  like  that 
of  Percopsis  exists  among  the  pirate  perches  ( Aphredoderidae) , 
v/hich  are  always  classed  as  Aca,nthopterygians.  The  adipose  fin 
is  purely  a physostomous  character  which  has  been  found  only  among 
salmon-like  fishes,  and  the  Siluridae  and  a fev;  deep  sea  forms  of 
the  Haplomi.  The  species  Columbia  transmontana  which  Eigenmann 
(l892)  describes,  perhaps  helps  to  strengthen  the  claim  that  Per- 
copsis is  an  Acanthopterygian.  Though  belonging  to  a different 
genus,  Eigenmann  describes  C.  transmontana  as  undoubtedly  of  the 
same  family  as  Percopsis.  It  has  two  stiff  strong  spiny  rays  in 
the  dorsal  and  one  or  two  in  the  anal  fin.  The  scales  on  the  an- 
terior part  of  the  body  are  more  deeply  ctenoid.  Both  Percopsis 
and  Columbia  have  the  ventrals  abdominal,  which  is  distinctly  char- 
acteristic of  isospondylous  fishes.  Their  pectoral  fins,  however 
are  a little  higher  laterally  than  is  usual  in  isospondylous  fishes. 

An  Acanthopterygian  fish  of  Europe,  the  Acerina  or  Gym- 
no  cephalous,  which  has  a naked  head  with  muciferous  spaces  in  the 

^The  specimens  which  I examined  were  at  the  height  of  sexual 
activity,  the  ovaries  greatly  enlarged,  the  females  being  extreme- 
ly full  bellied.  The  fish  at  other  times  surely  has  not  so  large 
a girth  and  more  compressed  than  the  specimens  I'  have  now. 


ll 


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-17- 


skull  resembles  Percopsis  in  this  respect  (Jordan  and  Evermann , 
1896).  They  (Jordan  and  Evermann)  hint  that  this  relationship 
of  Acerina  and  Percopsis  “may  be  more  than  accidental."  The  pre- 
maxillaries  bearing  the  teeth  and  forming  the  entire  upper  margin 
of  the  mouth  is  true  of  the  Acanthopterygians  and  of  the  family 
Ga  didae. 

Rathke  (l837)  gave  the  first  extensive  account  of  the 
digestive  tract  of  European  fishes.  He  divides  the  alimentary 
tract  into  three  main  divisions,  the  oesophagus,  stomach,  and 
truncogaster  or  intestine.  In  most  fishes  the  stomach  is  divided 
in  two  regions,  cardiac  and  pyloris.  The  intestine  has  a part 
v;ith  pyloric  caeca  and  a longer  tube  reaching  from  the  pyloric 
caecal  region  to  the  anus.  The  pars  pyloric  of  the  stomach  is 
often  drawTi  out  in  a more  or  less  elongated  sac  which  he  calls 
the  "blind  sac."  Thus  the  intestine  arises  not  from  the  extreme 
posterior  end  of  the  pyloric  part  of  the  stomach,  but  more  or 
less  toward  the  middle,  the  length  and  width  of  the  blind  sac 
being  roughly  proportional  to  the  length  and  width  of  the  body 
cavity.  The  blind  sac  predominates  in  the  Acanthopterygii.  Per- 
copsis has  no  blind  sac  and  in  this  respect  it  differs  from  the 
Ac  an thop terygian  type.  The  canal  of  Percopsis  does  resemble  that 
of  Mullus  ba.rbatus  in  respect  to  the  appendices  pyloricae  which 
are  in  small  number  and  distributed  evenly  on  the  right  and  left 
side  of  the  intestine,  but  the  intestine  of  M.  barbatus  differs 
from  Percopsis  in  its  being  longer  and  making  tv/o  bends  instead 
of  one  before  it  reaches  the  exterior.  The  stomach,  too,  is  short 


jH*.. ' 


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-18- 


like  that  of  Percopsis  tut  differs  from  Percopsis  in  that  it  has 
a sme.ll  tlind  sac. 

Jacotshagen  (1912)  has  putlished  on  the  alimentary  tract 
of  fishes.  Besides  his  own  individual  work,  he  quotes  from  many 
of  his  predecessors  and  contemporaries.  He  notes  that  in  many  of 
the  genera  of  the  Salmonidae,  especially  the  genus  Salmo,  there 
is  no  tlind  sac  (except  in  Salmo  autumnalis)  and  the  numter  of 
pyloric  appendages  is  very  variatle,  from  288  in  S.  unimaculatus 
to  20  in  S.  hoodii.  The  appendages,  however,  are  arranged  in 

I 

equal  numter  in  a linear  series  on  the  rigjit  and  left  side  of  the 
intestine.  The  canal  is  siphonal,  a double  tent  tube,  the  stomach 
receiving  one  tend,  the  intestine  one;  the  shorter  aim  of  the 
intestine  receiving  the  pyloric  appendages.  The  canal  of  salmo 
then  is  very  like  that  of  Percopsis  if  the  numter  of  pyloric  appen 
dages  were  reduced. 

The  simple  swim  bladder  v/ith  no  connection  with  the 
alimentary  tract  places  Percopsis  outside  the  pale  of  physostomous 
fishes.  It  has  always  heretofore  teen  described  as  being  physos- 
tomous. Gunther  ( 1866)  says  that  it  probably  has  a pneumatic 
duct.  He  placed  it  in  his  order  Physostorai  and  gave  it  a place 
just  after  his  family  Salmonidae  Vvith  the  family  name  of  Percop- 
sidae.  Jordan  and  Evermann  (l896)  say  that  the  "air  bladder  is 
present  with  a band  of  connective  tissue  v/hich  is  apparently  with 
a-  rudimentary  duct."  They  place  it  among  the  very  first  of  the 
Ac  an thopterygian  fishes  making  a sub-order  Salmopercae  of  it. 
Kingsley  (1899)  does  the  same.  Browntree  (l903)  dissected  a large 


V 


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number  of  supposedly  physostomous  fishes  of  different  families  and  | 
genera  to  determine  the  position  of  the  pneumatic  ducts.  Among  | 

these  fishes  which  he  dissected  were  two  specimens  of  Percopsis  j 

guttatus  and  one  of  Columbia  transmontana.  He  says  that  they  are  I 

I 

physostomous  and  that  the  pneumatic  duct  opens  to  the  right  side 
of  the  oesophagus.  Boulenger  (1904)  claims  P.  guttatus  to  be  phy- 
sostomous but  places  it  among  the  Haplomi  because  of  skeletal  struc- 
tures. Goodrich  also  claims  for  it  a pneumatic  duct,  but  like  Jor- 
dan and  Evermann,  gives  it  a place  as  lowest  of  the  Acanthoptery- 
gians. 

I have  made  sections  of  the  place  where  the  duct  should 
be,  and  I find  that  there  is  no  duct  present,  either  open  or  atro- 
phied, between  the  alimentary  canal  and  the  swim  bladder  of  Peroop- 
sis.  My  observations  agree  with  those  of  Regan  (1909  and  1911), 
who  says,  "The  Salmopercae  are  physoolystlc;  I cannot  find  any 
trace  of  a pneumatic  duct.  In  this  I am  confirmed  by  Dr.  W.  G. 
Ridewood,  who  kindly  examined  an  example  of  Columbia  transmontana." 
Thus  Percopsis  is  not  a physostomous  fish  and  cannot  be  classed  as 
such  upon  the  basis  of  the  swim  bladder.  The  simple  ductless  sac- 
like  bladder  is  mors  like  that  found  in  the  Acanthoptsrygii . 

The  brain  of  Percopsis  in  external  appearance  resembles 
that  of  the  salmon  and  perches  as  to  relative  size  of  optic  lobes, 
cerebrum  and  medulla  oblongata.  It  differs  materially  from  the 
Salmonidae  in  that  the  csrebsllVJm  is  not  so  large  as  that  of  the 
Salmonidae;  not  extending  far  back  on  the  myelencephalon j < 

and  that  in  the  Percopsidae  the  olfactory  lobes  are  directly 


-20- 

oonnected  to  the  nasal  sacs  being  united  to  the  telencephalon 

by  an  olfactory  tract  (tractus  olfactorus),  while  in  the  salmon 

the  olfactory  lobes  are  adjacent  to  the  telencephalon,  separated 

only  by  a shallow  circumscribed  groove  and  the  olfactory  nerves 

greatly  elongated.  The  olfactory  lobes  and  nerves  of  Percopsie 

are  like  those  of  the  salmon  and  trout  except  the  external  struc- 

which 

ture  of  the  brain  of  Percopsi^does  not  differ  from  that  of  per- 
ches. 

The  position  of  the  olfactory  lobes  in  Percopsis  is 
comparable  to  that  found  in  those  physostomous  fishes  included 
in  the  Siluridae,  Cyprinidae  and  of  those  Isoapondylous  fishes 
of  the  family  Hyodontidae.  According  to  Herrick  (1891)  these 
fishes  all  have  a long  olfactory  tract  with  olfactory  bulb  adja- 
cent to  the  nasal  sacs.  This  condition  of  nasal  organs  to  olfac- 
tory nerve  is  also  found  in  the  Gadidae  (Goodrich  1908).  Of 
these  fishes  which  Herrick  describes,  the  brain  of  Hyodon  tumidus, 
though  longer  and  less  compact,  is  most  comparable  to  that  of 
Percopsis. 

Stannius  (1854)  mentions  28  families  and  genera  of  Tele- 
ostean  fishes  which  had  been  investigated  up  to  his  time.^  These 

So  bei  alien  bisher  untersuchten  Percoi'den,  Cataphracten,  Scidn- 
ofden,  Sparoi’den,  Mugiloi'den,  Squamipennen,  Scombero3!den,  Tdni- 
ofden,  Thentyern,  Blennioi'den,  Gobiofden,  Clycopoden,  Pediculaten, 
Labrofden,  Chromiden,  Scomber-Esoces,  Pleuronectiden,  Fistulares, 
Esocinen,  Salmoniden,  Clupefden,  Murdnofden,  Gymnotini,  Lopho- 
branchii,  PlectognathiT-Oadofdei , Siluroi'dei,  Cyprinoldei . 


r^'’’ • ;*•  . i- v*v  ..•■„-*■!  . . -’.V  . : i' 


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. ■'.  “ ‘ .’ ^Ai  •"'‘‘'•T-t'  ■ ’’  y^'~'~\  ■■•"■":*''***^:.-'  ■!*.#>[?-■“•  T* »-  .j 


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-21- 

inoluded  a wide  range  of  fishes  both  physostomous  and  physoclia- 
tous  fishes.  All  have  olfactory  lobes  attached  directly  to  the 
telencephalon  except  those  families  of  the  Gadofdea,  SiluroSdea, 
and  Cyprinoldea.  The  Siluridae  and  Cyprinidae  are  classed  as  low 
type  fishes,  yet  the  Anacanthini,  of  which  the  Gadidae  is  a family, 
are  one  of  the  highest  types.  The  former  type  - the  long  olfactory 
nerve  - seems  to  predominate,  so  it  is  hard  to  say  which  condi- 
tion is  most  primitive.  From  general  structure  it  is  not  possible 
that  Percopsis  is  as  high  a type  as  the  cod.  One  thing  is  certain: 
the  brain  has  mixed  characteristics,  but  resembles  the  type  of 
brain  found  in  the  Percidae,  Hyondontidae  and  Gadidae. 

V.  Conclusion 

To  determine  the  position  of  Percopsis  guttatus  by  ana- 
tomical structure  other  than  skeletal  is  not  easy.  The  naked  head; 
small  adipose  fin;  the  small  anterior  dorsal  fin  of  soft  articu- 
lated branched  rays;  the  ventral  fins  almost  abdominal  in  posi- 
tion; and  the  slphonal  alimentary  canal  with  its  linear  arrange- 
ment of  pyloric  caecae,  but  with  no  blind  sac;  show  decided 
Isospondylous  characteristics.  On  the  other  hand,  it  is  just  as 
strikingly  Aoanthopt erygian  for  there  is  present  two  true  dorsal 
fin  spines;  one  anal  spine,  the  premaxi liar ies  form  the  margin 
of  the  jaws  and  bear  teeth;  the  scales  are  ctenoid;  the  body 
is  perch-like  in  shape,  and  the  swim  bladder  is  entirely  ductless. 

In  respect  to  the  olfactory  region,  the  brain  is  the 


. .--.w 

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vri,:  V ■'  ■ ■■.  ' ;■  .Silifi.  ,|1^' ^ 


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-32- 

type  that  belongs  to  the  more  primitive  fishes,  suoh  as  the  Cyprln- 
idae  or  Siluridae.  In  these  fishes  the  olfactory  bulbs  are  ;)oined 
to  the  nasal  sacs  and  are  connected  to  the  telencephalon  by  a long 
olfactory  tract.  In  this  respect  Percopsis  guttatus  is  primitive. 
But  even  the  resemblance  of  the  brain  of  Percopsis  to  the  Siluri- 
dae and  C^^’prinidae  does  not  prove  that  it  belongs  to  the  Ostario- 
physi,  for  the  Weberian  apparatus  which  predominates  in  these 
forms  is  not  present  in  Percopsis. 

If  the  skeletal  structures  are  excluded,  the  greatest 
amount  of  evidence  tends  to  show  that  the  Percopsidae  are  primi- 
tive Acanthoptsrygians.  The  perooid  mouth,  fin  spines,  and  duct- 
less air  bladder  having  the  most  weight  in  favor  of  the  Acanthop- 
terygii.  The  Percopsidae  seem  to  have  arisen  from  those  types  of 
fishes  which  were  Isospondylous  in  regard  to  external  structure 
and  viscera,  but  retained  the  brain  structure  of  the  Eventognathi . 
The  Percopsidae  are  transitional  forms,  having  entered  the  thres- 
hold of  the  Aoanthopterygii , but  never  developing  farther,  have 
retained  some  archaic  features. 


5i^, 


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tg  ’i'iMfi*  •’'  •*  ■■  *'  ■ ■■  ■•*.  f.'  >•%  i ■#. y 

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4 


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-23- 


VI.  Bibliography 

Though  all  the  authors  mentioned  in  this  bibliography 
have  not  been  mentioned  in  this  text,  their  work  has  been  con- 
sulted and  the  contents  in  respect  to  the  subject  matter  pertain- 
ing to  this  paper  have  been  noted. 


Agassiz,  Louis 

1850  Lake  Superior,  pp.  384-289. 

Boulenger,  George  Albert 

1904  A Synopsis  of  the  Suborders  and  Families  of  Telsos- 
tean  Fishes.  Annals  and  Magazine  of  Natural  History. 
Vol.  13:  161-190. 

Boulenger,  George  Albert 

1904  Teleostei  (Systematic  Part).  The  Cambridge  Natural 
History.  Vol.  7. 

Browntree,  Walter  S. 

1903  On  some  Points  in  the  Visceral  Anatomy  of  the  Chara- 
oinidae,  with  an  Enquiry  into  the  Relations  of  the 
Ductus  pneumaticus  in  the  Physostomi  generally.  Trans. 
Linnean  Society  of  London,  pp.  47-61. 

Dahlgren,  Ulric 

1898  The  Maxillary  and  Mandibular  Breathing  Valves  of 

Teleost  Fishes.  Zoological  Bulletin,  Vol.  2:  117-124. 
Dean,  Bashford 

1895  Fishes,  Living  and  Fossil. 


■ * 

\r  ,'  ■ ' ‘ 

j -nai! 


>»>  M 


:[ttov^  4fS£fp;f  ^7X&^ 

■;  ■«  ■,..  . ’.  v!1d  ^ - ■'•  '■  ?•■  :'v‘?  I :tv 

■V.  .-a:-  !».  : r-  VIS'’: -)*^;.  '*w  • *. 


»/■ 


tjE'^Jgl'i  .T  • - 


‘7ijOO;+>T  £ 

,v.l« 


'r-rJ 

■■'•  » '"'  1^  ’ ' ■■’  ■ •■'■  & ' FT? 

TvMc'tSE  ■‘?J',fltS'-*6.;«^W4r  A ■ ♦«&*•  ■»n'^*a*' 

' ' ir!^>'^ 

v‘'  ' m'^ 


.m  ;!'S«i 


*f>’ 


. . . '.,  ^-A  .:;■  -T : ‘K.»,  m 

' ^ ' v''//  ;^,. 


i*'  ■"'  li  • * & 

»;«xag;tfiaj:a5)r  :s 

* .^y^'ldf*  r S ■*_  , . t 5-^  ■*  B 


-24- 

Eigenmann,  Carl  H. 

1893  The  Percopsidae  of  the  Pacific  Slope.  Science, 

October  21,  pp.  233-234. 

Gegenbauer,  Carl 

1898  Vergluchende  Anatomie  der  Wirbelthiere . Band  1. 

Goodrich,  E,  6. 

1909  Vertebrata  Craniata  (First  Fascicle:  Clyclostomes 
and  Fishes)  in  "A  Treatise  of  Zoology”  edited  by 
E.  Ray  Rankest er.  Part  IX. 

Got t ache,  G.  M, 

1835  Vergluchende  Anatomie  des  Gehirns  des  Grdtenf ische, 
Reichert  Archiv,  pp.  244-294;  433-486. 

Gdnther,  Dr.  Albert 

1859  A Catalogue  of  Aoanthopterygean  Fishes.  Vol.  1-8. 

Gdnther,  Dr.  Albert 

1880  An  Introduction  to  the  Study  of  Fishes. 

Eerrick,  C.  L.  and  C.  Judson 

1691  Contribution  to  the  Morphology  of  the  Brain  of  Bony 
Fishes.  Journal  of  Comparative  Neurology.  Vol.  1: 
311-245. 

Jacob Shagen,  Dr.  Edward 

1912  Enter suchungen  iiber  das  Darmsystem  der  Fische  und 

Dipnoer.  Jenaische  Zeitschrift  ftlr  Naturwissenschaf t . 
Teil  II  Material,  zur  vergluoh.  Anat . des  Darmkanal 
der  Teleostomen  - pp.  373-810. 


V 


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'“;',W-.5' 


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• ^ '•■  I'^prV'V’  •'  ' ’-kC.'.n  ?!■.  '.’■W^g  "-yiH^BPl'r 

^ ■‘'.V-  X2ii:| 

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. >V.* 


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^ ^ , 'i  ■ ./• ; • ■■’  '•!.4’i'''' >!•■>■%,  * ' iJS 


.n 


■5.  > . - • ' . _ ■ a'‘E^  • I • « ■ ■ 

^ ■'  -3"  -■  V -"^  '''  K , . ’':'  "A'  -..  j> 


u:  , # V ‘•I'V  • : *3[.Csi  ,.i  ;• 

^ V'  ' .'  ; » ‘•i  . / *;>  ’ •••-..  /• ' . ,^'A,  -r  ■ '^‘v^  . \f  '‘‘  

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' • ■*  • . "'■  ’ .,'  / • '.  J'S.  . v ' :'C‘V  '0'>  - 


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vn  ( 


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-25- 

Jordan,  David  Starr,  and  Evermann,  B.  W. 

1896  The  Fishes  of  North  and  Middle  America.  Bui.  U.  S. 

Nat . Museum . 

Jordan,  David  Starr 

1905  Guide  to  the  Study  of  Fishes. 

Maoallum,  A.  B. 

1884  Alimentary  Canal,  Liver,  Pancreas,  and  Air  Bladder  of 
Amiurus  catus.  Proo.  Can.  Inst.  Toronto. 

Oppel,  Albert,  Dr.  Med. 

1896-1913  Lehrbuoh  der  vergleichenden  mikroskopichen 
Anatomie  der  Wirbelthiere . Jena. 

Parker,  Thomas  Jeffrey 

1884  A Course  of  Instruction  in  Zootomy,  pp.  86-129. 

Rathke,  Heinrich 

1837  Zur  Anatomie  der  Fische.  Reichert  Archiv.  Part  II 
pp.  305-356.  Hierzu  Taf.  XVII  - XIX. 

Regan,  C.  Tate 

1909  The  Classification  of  Teleostean  Fishes.  Ann.  and 
Mag.  Nat.  Hist.  Vol.  3:  75-86. 

Regan,  C.  Tate 

1911  Anatomy  and  Classification  of  Teleostean  Fishes  of  the 
Order  Salmopsrcae.  Ann.  and  Mag.  Nat.  Hist.  Vol.  7. 
Stannius,  Herman 

1854  Handbuch  der  Anatomie  der  Wirbelthiere.  Vol.  2, 

Vogt,  Carl,  und  Yung,  Emil 

1885  Lehrbuch  der  Praktischen  Vergleichenden  Anatomie. 
Zweite  Bund,  pp.  470-543. 


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PLATE  I 


1.  Brain  (ventral  view) 

2.  Brain  (lateral  view) 

3.  Brain  (dorsal  view) 


cer. 

- 

- 

- - cerebrum 

cert. 

- 

- - cerebellum 

CO. 

- 

- 

- - optic  chiasraa 

hyp. 

- 

- 

- - hypophysis 

inf. 

- 

- 

- - infundibulum 

li. 

- 

- 

- - lobi  inferiores 

med. 

- 

- 

- - medulla  oblongata 

0 II 

- 

- 

- - optic  nerve 

ol. 

- 

- 

- - olfactory  lobe 

olt. 

- 

- 

- - olfactory  tract 

opt. 

1, 

“ - optic  lobe 

V. 

- 

Nervus  trigeminalis 

VI. 

- 

Nervus  abduscens 

VII. 

- 

Nervus  facialis 

VIII. 

- 

Nervus  acusticus 

IX. 

- 

Glossopharyn geal 

X. 

- 

Vagus 

4.  Alimentary  Tract 

an.  - - - - anus 

cd.  - - - - cardiac  (stomach) 

in.  - - - - intestine 

li.  - - - - liver 

oe.  - - - - oesophagus 

pyl.-  - - - pyloric  (stomach) 

pylc.  - - - pyloric  caecae 

sp.  - - - - spleen 

5.  Stomach 

6.  Swim  Bladder  (ventral  view) 

7.  Swim  Bladder  (lateral  view) 

ret.  - - - rete  mirahle 
art.  - - - artery 


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The  work  of  this  paper  was  carried  on  in  the  Zoological 


Laboratories  of 
of  Professor  J. 
cere  thanks  for 


the  University  of  Illinois,  under  the  direction 
S.  Kingsley,  to  whom  the  writer  extends  his  sin 
his  guidance  and  helpful  suggestions. 


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